The object of the invention is a hammer (tool machine), in particular for recoilless high speed impact cutters for the cutting/shearing of wire and/or rod sections, generally for wire processing machines, in particular as part of single or multistage presses where the cutting cycle is integrated into the overall operation of the press.
A device for cutting rod sections on automatic multistage crossfeed presses is known from DE 25 26 151 C3. Here, a striker (hammer) located at the end of a cam-guided striking lever indirectly strikes a sliding blade carrier. Upon the impact of the striker, the sliding blade carrier jumps forward with a high initial velocity (conservation of momentum). Then, coil springs return the sliding blade carrier back into contact with the striker so that the striker can move the sliding blade carrier to a transfer position where the rod section is picked up by a transport gripper.
This process has the disadvantage that the impact of the striker on the sliding blade carrier generates recoil which causes the striker to bounce off the sliding blade carrier; this, in turn, imposes a high stress on the cam gear driving the striker.
For this reason, the invention intends to solve the problem of avoiding the recoil caused by the impact of the striker on the sliding blade carrier, so that the cam gear is exposed only to a force with limited damaging effect.
The invention provides a machine tool hammer specifically intended for impact cutters for cutting sections of wire and/or rods. The tool includes a striker that can be driven back and forth at a selected impact speed, and a tool carrier on which the striker impacts. A separate mass carrier in the form of an auxiliary lever is located on the back side of the striker, facing away from the tool carrier. Starting at an initial position, the mass carrier stays in contact with the striker while following its movement towards the tool carrier until the striker strikes the tool carrier. At this point the movement of the mass carrier stops. The striker continues moving, driving the tool carrier from its starting position to cut the work piece. The striker then changes direction, allowing the tool carrier to return to its starting position, and thereafter taking the mass carrier back to its own starting position. The moving mass of the mass carrier is larger by the amount 2A/v2 than the moving mass of the tool carrier, where A is the work required to effect the cutting operation and v the operating speed to be provided by the tool carrier.
By causing the mass of the mass carrier to be moved by the striker, the cam-driven striker serves only as an intermediate buffer for the tool carrier, to which the momentum of the mass carrier is transferred in such manner that the momentum of the mass carrier and striker combined is equal to the momentum of tool carrier and striker combined.